The present invention relates to a percussion tool which has a percussion element and a hammer which is reciprocated between a percussion position for hitting the percussion element and a standby position so that an object is broken by the percussion element repeatingly hit by the reciprocating hammer.
Such percussion tool is used to break an asphalt paving in repairing a pavement or to break walls of a building for repair or reconstruction thereof. In such application, a top point of a percussion element of the tool, i.e., chisel, abuts an object to be broken and, in such state of the chisel, it is hit by the hammer repeatingly to push the chisel into the object gradually to thereby crack the object.
In the conventional percussion tool in which the hammer in the standby position is moved toward the percussion position by supplying a pressurized fluid such as air, there are considerable vibrations produced due to mainly reactive forces of the supplied air during the movement of the hammer toward the percussion position.
There are also considerable vibrations produced immediately after the hammer hits the chisel. These vibrations are produced due to the fact that the chisel is generally mounted through a resilient means such as springs on a frame of the tool and there are reactive forces produced in these springs immediately after the hammer hits the chisel.
It has been known that, among these vibrations, the vibrations produced immediately after the hitting by the hammer can be minimized by supporting the chisel axially slidably. However, the problem of vibrations due to the reaction forces of the compressed air etc., have been left as they are. In using the percussion tool having the chisel and the hammer, the tool is usually hand held. However, since the conventional percussion tool produces considerable vibrations as above mentioned, it is impossible to use if for a prolonged time period.
The percussion tool may be supported by a suitable machine, e.g., a backhoe. Even in such case, the machine must be large enough to withstand the vibrations, which is disadvantageous in view of economy.